My overengineered 3d printer

[student_Machinist]

Hey guys
I know this isnt really the focus of this forum but someone might find it interesting, that and i need as much help as i can get
I started this printer when i was 18 (im 19 almost 20 now) and its been complete for quite some time but ive been messing around with a massive issue for the past 10 months that ive never been able to get past. But first here are the pics

Now comes the problem, Ive been having isues with the extruder blocking due to the filament forming a plug after a while. this results in many partial prints, most of which are around 5mm when they fail

The extruder its self is designed around/ copied from the makerbot mk7 so it should work but no mater what i do i still end up with the same issue. Note a couple of the pics have the previous extruder that i swaped out for the mk7 style one. Im currently running Slic3r and mach3 with linistepper controllers

One thing that im wondering about is that im printing with cheap chinese PLA so this could be the problem but i dont have any high quality plastic to compare to.
Feel free to ask any questions on the settup etc but i would really appreciate and help as ive spent soooo long working on this thing that failure is not an option

BTW sorry if the pics are massive, they look ok on my computer so fingers crossed
Cheers
Jonathan Feist

 

[student_Machinist]

Btw whoever can guess what im trying to print gets a free interweb cookie

 

[scruffy]

Im not going to be much help but Ive been looking at doing something like this, Id like to see how you solve your problem. What are you using to heat the plastic?

 

[dave-in-england]

Seems to me that the print head is right on the lower temperature limits of the plastic melt temperature,

it is blocking the nozzle because the plastic is cooling too quickly before it has a chance to flow onto the part,

and is slowly solidifying inside the nozzle, restricting the flow.

Try increasing the nozzle temperature by 20 degrees C.

 

[dman]

i'd guess it's a v8 block. possibly a form to cast it in metal.

as far as your clogging problems sounds like not enough heat. it can get up to temp but once the wire starts flowing it's pulling heat away faster than the element can create it. i dont know how your heat is regulated or how many more watts you can pump into it though. wish i knew more about plastics and 3d printers.

maybe you can sow the speeds on the feed rate of the head and of the plastic wire.

 

[student_Machinist]

i'd guess it's a v8 block. possibly a form to cast it in metal.

as far as your clogging problems sounds like not enough heat. it can get up to temp but once the wire starts flowing it's pulling heat away faster than the element can create it. i dont know how your heat is regulated or how many more watts you can pump into it though. wish i knew more about plastics and 3d printers.

maybe you can sow the speeds on the feed rate of the head and of the plastic wire.

You has cookie its steves demon v8 ive started work on the block and thought it would be nice to have a 3d model of what i was making
the first print i did on it was steves block as pictured below, the resolution is terrible as it wasnt really calibrated at that point but it did work, I switched to pla after realizing the fumes from abs give me bad migranes :wall: ever since then i havnt been able to get it to work

 

[student_Machinist]

Im not going to be much help but Ive been looking at doing something like this, Id like to see how you solve your problem. What are you using to heat the plastic?

Im using two 5.8ohm(or thereabouts) wire wound enamel resistors in paralell. they are powered from 12v and controlled via a cheap PID controller

 

[student_Machinist]

Seems to me that the print head is right on the lower temperature limits of the plastic melt temperature,

it is blocking the nozzle because the plastic is cooling too quickly before it has a chance to flow onto the part,

and is slowly solidifying inside the nozzle, restricting the flow.

Try increasing the nozzle temperature by 20 degrees C.

Thats what id initially thought but it doesn't seem to be the case. the pictured failed print was done at 180 degrees but ive tried temperatures up to 220 with the same result, i could try higher but from what ive heard 220 is rather exesive

 

[dman]

Thats what id initially thought but it doesn't seem to be the case. the pictured failed print was done at 180 degrees but ive tried temperatures up to 220 with the same result, i could try higher but from what ive heard 220 is rather exesive

hmm. well on one hand having the heat doesn't mean its making it into the plastic on the other hand if raising the heat made no difference I'm not sure what to tell you unless the heat transfer is very poor.

how are you measuring the temp? and what is the nozzle made from? what is the clearance of the nozzle to the plastic wire? what feeds the plastic? and is the ID of the nozzle polished smooth?

 

[S3MIH3MI]

Have you tried a purge cycle every once in a while. We run adhesives and sealer steady, and every so many jobs we need to purge the nozzles or the flow rate becomes too low and fails..

 

[Dave Sohlstrom]

PLA is a PITA. pla will swell when heated and if you stop the print for any reason and do not lower your hot end temp the heat migrates up your teflon tube and swells the pla causing a blockage. Easy answer is change to ABS and a heated bed.

A good forum on 3D printing is here http://forum.seemecnc.com/ You can find several threads on PLA problems.

Dave

 

[student_Machinist]

Have you tried a purge cycle every once in a while. We run adhesives and sealer steady, and every so many jobs we need to purge the nozzles or the flow rate becomes too low and fails..

yea i purge the extruder every time i attempt a print.

I just tried printing with abs and am still having the same issue

 

[student_Machinist]

Its working!!! All i had to do was shorten the thermal barrier so that almost all of the cold side was in contact with the heat sink. It still needs alot of fine tuning but im happy it will now make it through a print quite reliably. The biggest issue that ive found now is that Slic3r produces very jerky/rough movement around curves. do you think this could be resolved with the CV mode in mach3??

 

[stevehuckss396]

s very jerky/rough movement around curves. do you think this could be resolved with the CV mode in mach3??

Possibly. Could also be the solid model has too little facits making up the curve. The more facits, the smoother the corner

 

[motorman46]

Hi Student_machinist,

That is a very nice printer. You really do nice machine work also. I can't help with the nozzle clogging problem, but I do have a question concerning the design of the Y-axis drive system. I am in the beginning stages of building the Prusa Mendel 3D printer so I looked at your mechanism for driving the Y-axis closely. It appears your drive belt to pulley interface utilizes the back of the belt instead of the tooth side. I was wondering if you get any Y-axis drift because of this?

Regards,

Julian

 

[agmachado]

Very cool !

I think that soon it will not be difficult to design a printer for sand molds, similar to this...

[ame]http://www.youtube.com/watch?v=Z8MaVaqNr3U[/ame]

Cheers,

Alexandre

 

[student_Machinist]

Hi Student_machinist,

That is a very nice printer. You really do nice machine work also. I can't help with the nozzle clogging problem, but I do have a question concerning the design of the Y-axis drive system. I am in the beginning stages of building the Prusa Mendel 3D printer so I looked at your mechanism for driving the Y-axis closely. It appears your drive belt to pulley interface utilizes the back of the belt instead of the tooth side. I was wondering if you get any Y-axis drift because of this?

Regards,

Julian

Thanks I appreciate that. The carriage doesn't need to be driven by the toothed side as its a sympathetic pulley arrangement. All that the motor is doing is shortening one loop while making the other side longer. its kind of hard to explain but to answer your question, there is no drift as its impossible to move in the yaxis without the motor spinning. I quite like the arrangement as it keeps the weight of the second motor on the frame resulting in higher acceleration.